Relax, it's competely normal.

It must have been exactly fifteen minutes after the bell tolled over Sybal Heim. Arabelle hadn’t really been expecting anything exactly; it was more accurate to say that it all felt too surreal for her to react. Projecting the face of normality seemed to be her frozen stiff solution for staying calm until her mind could catch up with reality. What had they said? A change was coming with the night? She would change?

It actually happened in a matter of seconds but the mind holds memory in strange ways. Tense and shocked as she seemed to be, any surprise filled her mind to the brim with sights, sounds, sensations. She could remember every movement and every image that progressed through it all to such a level that, even though it didn’t actually feel like it lasted longer, she remembered it like it was a stone sinking through molasses.
She was sitting down, trying her utmost to ignore the transformation starting from her hand. She was vanishing, bone and skin evaporating into a white smoke and disappearing into nothingness. It came with sensation as well. She wanted to move, to jump, and to run away. Every fluttering heartbeat brought her nearer to a mad dash across the floor, the hallways and anything she found outside without a care for direction. Panicking as she was she had decided that the motions of her lungs weren’t as crucial as processing each instance of reality seeming to crumble within her.

She had already sprung from her chair at this point, Rationality having deemed her a lost cause. Her limbs billowed away to bring oblivion inching closer to her heart and mind. A blind haze of panic covered her eyes, making her lose sight of everything except the strange chaotic sensations and the mindless drive to race away from the nothing chasing her. Her head was next, leaving a brief haunting image to anyone around her before she was gone completely, leaving nothing but a pale mist.

Of course, for the other people it didn’t seem to happen quite so slowly.